Comparable TNF-alpha, IFN-gamma and GM-CSF production by purified normal marrow CD3 cells in response to horse anti-lymphocyte and rabbit antithymocyte globulin

Eltrombopag Preserves the Clonogenic Potential of Hematopoietic Stem Cells During Treatment With Antithymocyte Globulin in Patients With Aplastic Anemia

Aplastic anemia (AA) is frequently caused by a T-cell mediated autoimmune depletion of the hematopoietic stem and progenitor cell (HSPC) compartment. Immunosuppressive therapy (IST) with antithymocyte globulin (ATG) and cyclosporine represents the first-line treatment of AA. One side effect of ATG therapy is the release of proinflammatory cytokines such as interferon-gamma (IFN-γ), which is considered a major factor in the pathogenic autoimmune depletion of HSPC. Recently, eltrombopag (EPAG) was introduced for therapy of refractory AA patients due to its ability to bypass IFN-γ-mediated HSPC inhibition among other mechanisms. Clinical trials have evidenced that EPAG started simultaneously with IST leads to a higher response rate compared with its later administration schedules. We hypothesize that EPAG might protect HSPC from negative effects of ATG-induced release of cytokines. We observed a significant decrease in colony numbers when both healthy peripheral blood (PB) CD34⁺ cells and AA-derived bone marrow cells were cultured in the presence of serum from patients under ATG treatment, as compared with before treatment. Consistent with our hypothesis, this effect could be rescued by adding EPAG in vitro to both healthy and AA-derived cells. By employing an IFN-γ neutralizing antibody, we also demonstrated that the deleterious early ATG effects on the healthy PB CD34⁺ compartment were mediated at least partially by IFN-γ. Hence, we provide evidence for the hitherto unexplained clinical observation that concomitant use of EPAG in addition to IST comprising ATG leads to improved response in patients with AA.

Incidence and differential characteristics of culture-negative fever following pancreas transplantation with anti-thymocyte globulin induction

BACKGROUND

Limited data are available on the incidence and characteristics of culture-negative fever following pancreas transplantation (PTx) with anti-thymocyte globulin (ATG) induction. Our study aims to better define the features of culture-negative fever, so it can be delineated from infectious fever, hopefully helping clinicians to guide antibiotic therapy in this high-risk patient population.

METHODS

We performed a retrospective cohort study of postoperative fever among 198 consecutive patients undergoing PTx at our center between August 1, 2004 and December 31, 2014. Fever was classified as culture-negative if there was neither a positive culture nor a documented clinical diagnosis of infection.

RESULTS

Fever was identified in 113 patients; 66 were deemed to be infectious, 39 were culture-negative, and 8 were indeterminate. High body mass index of recipient (odds ratio 1.87, 95% confidence interval: 1.15-3.03, P = 0.011) was a significant factor associated with culture-negative fever in multivariate analysis. No patients with culture-negative fever were diagnosed with infiltrates or effusion on chest radiography. In addition, an increase in white blood cell count, C-reactive protein, and serum amylase was less prominent in culture-negative fever. Culture-negative fever developed most frequently at postoperative 7 or 14 days, showing a biphasic curve.

CONCLUSION

Culture-negative fever develops in a substantial proportion of patients early after PTx. The awareness of the possibility and clinical features of post-transplant culture-negative fever might help clinicians to guide antibiotic therapy in this high-risk patient population, especially following ATG induction and early steroid withdrawal.

Rabbit antithymocyte globulin (thymoglobulin): a review of its use in the prevention and treatment of acute renal allograft rejection

Rabbit antithymocyte globulin (rATG) [Thymoglobulin(R); Thymoglobuline(R)] is a purified, pasteurized preparation of polyclonal gamma immunoglobulin raised in rabbits against human thymocytes that is indicated for the prevention and/or treatment of renal transplant rejection in several countries worldwide. rATG induction in combination with immunosuppressive therapy is more effective in preventing episodes of acute renal graft rejection in adult renal transplant recipients than immunosuppressive therapy without induction. The efficacy of rATG induction is generally better than that of equine antithymocyte globulin (eATG) induction and generally no different from that of basiliximab or low-dose daclizumab induction in this patient population. However, in high-risk patients, rATG induction was more effective than daclizumab or basiliximab induction in preventing acute renal graft rejection. In the treatment of renal graft rejection in adult renal transplant recipients, rATG was more effective than eATG in terms of the successful response rate, although the agents generally did not differ with regard to most other endpoints. Both induction and treatment with rATG are generally well tolerated, although adverse events, such as fever, leukopenia and thrombocytopenia, appear more common with rATG than with other antibody preparations. The overall incidence of infection associated with rATG induction was generally no different from that seen with eATG or basiliximab induction, although was higher with rATG than with basiliximab in high-risk patients. The incidence of cytomegalovirus (CMV) disease generally did not differ between rATG and eATG induction, and there was no significant difference between rATG and daclizumab induction with regard to the incidence of CMV infections or the proportion of patients who received treatment for a CMV episode or infection. Relative to basiliximab, the incidence of CMV infection was generally higher with rATG, except in high-risk patients. In the treatment of acute renal rejection, the nature and incidence of infections were generally similar with rATG and eATG. The incidence of malignancies is generally low with rATG therapy and generally does not differ from that seen with other agents. Further prospective comparative studies would be beneficial in order to definitively position rATG with respect to other antibody preparations. In the meantime, available clinical data suggest that rATG is an effective and generally well tolerated option for the prevention and treatment of acute renal graft rejection in renal transplant recipients.

Upregulation of molecules associated with T-regulatory function by thymoglobulin pretreatment of human CD4+ cells

BACKGROUND

This study evaluated the immunologic effects of thymoglobulin in modulating human CD4+ cells.

METHODS

Human CD4+ cells were purified from peripheral blood mononuclear cells by negative selection method. CD4+ cells were pretreated with thymoglobulin and incubated for 72 hr. Cells and culture supernatants were collected and studied by real-time quantitative polymerase chain reaction, fluorescence activated cell scanning, multiplex cytokine assay, and mixed lymphocyte reaction (MLR).

RESULTS

Thymoglobulin pretreated CD4+ cells demonstrated up-regulation of gene transcripts for CTLA-4, OX40, forkhead box P3 (Foxp3), CD25, IFN-gamma, IL-10, and IL-2 as determined by real-time quantitative polymerase chain reaction. Fluorescence-activated cell scanning analysis demonstrated that CD4+ cells, pretreated with thymoglobulin, up-regulated CD25 expression on their surface, and the surface expression of CTLA-4 and OX40 and the expression of intracellular Foxp3 were observed in these CD4+CD25+ cells. Additionally, MLR demonstrated that thymoglobulin-pretreated cells partially inhibited proliferation of untreated autologous CD4+ cells in response to allogeneic cells. The high levels of IFN-gamma, IL-10, IL-2, and IL-4 were detected by multiplex cytokine assay in supernatants collected from cultures of thymoglobulin-pretreated CD4+ cells. The lymphocyte proliferation of allogeneic MLR was also partially blocked in the presence of supernatants from cultures of thymoglobulin-pretreated CD4+ cells.

CONCLUSIONS

This study demonstrates that the unique effects of thymoglobulin in modulating CD4+ cells may be an important mechanism for its action in inducing immunosuppression and transplant tolerance.

Excessive production of tumor necrosis factor-alpha by bone marrow T lymphocytes is essential in causing bone marrow failure in patients with aplastic anemia

Aplastic anemia (AA) is regarded as an immunological disorder because of the clinical effect of immunosuppressive therapy. Recent studies have reported that cytokines play an important role in the development of AA. In the present study, we measured levels of T-cell derived intracellular cytokine production in peripheral blood and bone marrow (BM) of patients with AA. We demonstrated that BM lymphocytes, particularly CD4(+) and CD8(+) T cells, in patients with AA produced significantly higher amounts of tumor necrosis factor-alpha (TNF-alpha), compared with lymphocytes in normal controls. We have previously reported that expression of TNF receptor (R)1 and TNFR2 in the CD34(+) CD38(-) and CD34(+) CD38(+) fractions of patients with AA is significantly higher than those in normal control. These results indicate that BM stem cells in patients with AA may possess high sensitivity to TNF-alpha. This in turn suggests that TNF-alpha affects hematopoiesis at an earlier stage in AA patients than in normal controls. We strongly support the hypothesis that a simultaneous increase in TNF-alpha production by BM lymphocytes and sensitivity of stem cells to TNF-alpha leads to BM failure in AA.

Involvement of Fas and TNF pathways in the induction of apoptosis of T cells by antithymocyte globulin

Antithymocyte globulin (ATG) is the treatment of choice for those aplastic anemia patients who are not suitable for bone marrow transplantation (BMT). ATG is also used for the treatment of rejections in organ transplantation and as a conditioning regimen in BMT. Despite the proven efficacy of ATG in these areas, its mechanism of action is not known. Profound T-cell lymphopenia observed in vivo with ATG treatment is supposed to contribute to its therapeutic effect. We have previously shown that apoptosis is one of the mechanisms responsible for ATG-induced lymphopenia. Our next objective was to investigate the effect of ATG on modulation of Fas and TNF pathways, the two main pathways of T-cell apoptosis. Maximum surface expression of Fas on T cells was observed after 24 h at an ATG dose of 100 microg/ml; at this dose 88% of cells expressed Fas as compared to 26% of untreated cells. Surface expression of FasL was found to peak after 24 h at an ATG dose of 1000 microg/ml when 34% of cells were positive for FasL as compared to 1.5% of untreated T cells. Tumor necrosis factor (TNF)-alpha production was found to be maximum after 6 h at 1000 microg/ml dose (20%) as measured by intracellular cytokine staining of T cells. TNF-alpha production was also measured by enzyme-linked immunosorbent assay (ELISA) in the supernatant of lymphocytes treated with ATG for 6 h. A dose-dependent increase in TNF-alpha production was found in these supernatants with a plateau being achieved at an ATG dose of 1000 micro g/ml. We conclude that ATG-induced apoptosis in T cells involves both Fas and TNF pathways and TNF-alpha is produced much earlier than Fas and FasL expression.

Acute respiratory distress syndrome after kidney transplantation: epidemiology, risk factors, and outcomes

OBJECTIVE

To determine the rate of the acute respiratory distress syndrome (ARDS) after kidney transplantation and to identify risk factors associated with the development of ARDS after kidney transplantation and outcomes for patients diagnosed with ARDS in this setting.

DESIGN

Retrospective analysis of the national registry for end-stage renal disease in the United States.

PATIENTS

We studied all patients who underwent kidney transplantation between July 1, 1994 and June 30, 1998 and identified patients diagnosed with ARDS. The diagnosis of ARDS was based on coding of patients records. We also compared the rate of ARDS after kidney transplantation with the rate of ARDS in the remainder of the U.S. population based on the results of the National Hospital Discharge Survey for 1997.

MEASUREMENTS AND MAIN RESULTS

During the study period, 42,190 kidney transplantations were performed in the United States and ARDS was diagnosed in 86 of these subjects (0.2%) resulting in an annualized rate of ARDS of 51.0 cases per 100,000 patients per year. The rate of ARDS after kidney transplantation was significantly higher than the reported rate of ARDS in the U.S. population (p <.050). Demographic factors, indications for transplantation, comorbid illness, antigen mismatch, cytomegalovirus status, and development of rejection did not correlate with the development of ARDS. Of the immunosuppressive agents (e.g., cyclosporine, FK-506, mycophenolate mofetil, azathioprine, OKT-3, antilymphocyte globulin), only the use of antilymphocyte globulin when used to treat rejection was linked with an increased risk for ARDS (odds ratio: 3.85; 95% confidence interval: 1.36 to 10.87). Subjects with graft failure were 2.70 (95% confidence interval: 1.33 to 5.52) times more likely to develop ARDS. The 28-day mortality in subjects with ARDS was 52.1%. The 3-yr survival after kidney transplantation was 88.9% in those without ARDS compared with 57.8% in persons with ARDS (p <.001).

CONCLUSIONS

Although ARDS is a rare event after kidney transplantation, undergoing renal transplantation increases the risk for ARDS. Among patients receiving kidney transplants, graft failure and the use of antilymphocyte globulin for rejection are associated with the development of ARDS. Patients who develop ARDS after kidney transplantation face significant mortality.

Hypoplastic myelodysplastic syndromes can be distinguished from acquired aplastic anaemia by bone marrow stem cell expression of the tumour necrosis factor receptor

It is often difficult to distinguish hypoplastic myelodysplastic syndrome (h-MDS) from acquired aplastic anaemia (AA), because of the considerable clinical, cytological and histological similarities between these two disorders. The distinction between AA and h-MDS is important because there is a higher risk of progression to acute leukaemia in patients with h-MDS compared with AA. Recent studies suggest that tumour necrosis factor-alpha (TNF-alpha) plays an important role in the development of AA. In order to determine the potential importance of TNF-alpha in the differential diagnosis of hypoplastic bone marrow (BM) disorders, we examined whether analysis ofTNF-receptor expression could be used as a tool to differentiate AA from h-MDS. Flow cytometric analysis revealed that BM stem cells (CD34+) from AA patients have markedly greater TNF receptor (R) 1 and TNFR2 expression than those from patients with MDS and h-MDS. We suggest that the BM stem cells with a high expression of TNFR in patients with AA may be potently sensitive to TNF-alpha stimulation of differentiation. Thus, we propose that quantification of TNFR expression in BM stem cellsmay be a useful method to distinguish AA from h-MDS.

Rabbit antithymocyte globulin (r-ATG) plus cyclosporine and granulocyte colony stimulating factor is an effective treatment for aplastic anaemia patients unresponsive to a first course of intensive immunosuppressive therapy. Gruppo Italiano Trapianto di Midollo Osseo (GITMO)

About 30% of patients with severe aplastic anaemia (SAA) unresponsive to one course of immunosuppressive (IS) therapy with antithymocyte or antilymphocyte globulin can achieve complete or partial remission after a second IS treatment. Among various second-line treatments, rabbit ATG (r-ATG) could represent a safe and effective alternative to horse ALG (h-ALG). In a multicentre study, 30 patients with SAA (17 males and 13 females, median age 21 years, range 2-67) not responding to a first course with h-ALG plus cyclosporin (CyA) and granulocyte colony stimulating factor (G-CSF), were given a second course using r-ATG (3.5 mg/kg/d for 5 d), CyA (5 mg/kg orally from day 1 to 180) and G-CSF (5 microg/kg subcutaneously from day 1 to 90). The median interval between first and second treatment was 151 d (range 58-361 d). No relevant side-effects were observed, but one patient died early during treatment because of sepsis. Overall response, defined as transfusion independence, was achieved in 23/30 (77%) patients after a median time of 95 d (range 14-377). Nine patients (30%) achieved complete remission (neutrophils >/=2.0 x 109/l, haemoglobin >/=11 g/dl and platelets >/=100 x 109/l). The overall survival rate was 93% with a median follow-up of 914 d (range 121-2278). So far, no patient has relapsed. Female gender was significantly associated with a poorer likelihood to respond (P = 0.0006). These data suggest that r-ATG is a safe and effective alternative to h-ALG for SAA patients unresponsive to first-line IS treatment.